In recent years, in order to increase an effect of dewatering a wet paper web in a press part of a paper-making process, the following method (so-called “shoe press”) has been widely used: one surface of the wet paper web disposed on a felt traveling at a high speed is pressed by a press roll and the other surface of the wet paper web is pressed by a pressure applying shoe with an endless belt interposed therebetween, thereby dewatering the wet paper web. In the shoe press, the endless belt (hereinafter, also referred to as “elastic belt”), in which a reinforcement base member is in one piece with a thermosetting polyurethane, has been conventionally used. The elastic belt for the press part normally has an outer circumferential surface provided with a multiplicity of drainage grooves along the circumferential direction. Moreover, in recent years, use of such shoe press and elastic belt has been considered for a calender process in which a surface of paper is smoothened to provide luster. Further, particularly in the paper making at a high speed, a sheet transfer elastic belt for preventing cut of paper and stably transferring the wet paper web may be also nipped in the shoe press.
In the shoe press, the belt is severely bent and pressed repeatedly between the press roll and the pressure applying shoe. Such an elastic belt is replaced due to, for example, occurrence of cracks and reduction of the volume, i.e., VV (void volume) of the drainage grooves. Japanese Patent Laying-Open No. 2002-146694 (Patent Document 1), Japanese Patent Laying-Open No. 2005-097806 (Patent Document 2), or the like proposes a method of preventing occurrence of cracks. Patent Document 1 discloses a shoe press belt in which a polyurethane constituting the outer circumferential surface of the shoe press belt is constituted of a composition including an urethane prepolymer having an isocyanate group at its terminal and a curing agent containing dimethylthiotoluenediamine. Patent Document 2 discloses to reduce a belt thickness of a shoe press belt at regions, which correspond to respective ends of a pressure applying shoe in the width direction and in which cracks are likely to be generated, as compared with a belt thickness of the central region of the shoe press belt. By using such a method, occurrence of cracks due to short-time use can be prevented. Therefore, based on a degree of reduction of the VV of the drainage grooves, the elastic belt can be replaced as planned.